Shredded Serpentine Belt on Volvo XC60 Causes Major Engine Damage!

All Head Services recently received a cylinder head from a customer for repair.

The cylinder head was from a 2010 Volvo XC60 with a 5 cylinder 2.4 litre diesel turbo D5244T engine.

The serpentine belt that drives all the accessories had frayed and part of the belt managed to get between the timing cover, which in turn caused the timing belt to dislodge.

The cylinder head was inspected and had smashed all the value lifter bores in the cylinder head and bent all the valves.

The cylinder head was beyond repair and another cylinder head could not be sourced giving the customer no other option than to fit a used engine.

It is common issue for the serpentine belt to cause this type of expensive failure and it is important that the serpentine belts and tensioners are replaced at the correct intervals or when showing signs of wear.

Replacement intervals for serpentine belts and timing belt.

Up to Engine #884797

Auxiliary Drive Belt Tensioner – Renew

At 60000km or 120 Months

At 180000km or 120 months and then every 90000km or 120 months

Auxiliary Drive Belt, Inner – Renew

Every 180000km or 120 months

Auxiliary Drive Belt, Outer – Renew

At 6000km or 120 months

At 180000km or 120 months then every 90000km or 120 months


From Engine # 884798 –  

Auxiliary Drive Belt Tensioner – Renew

Every 90000 km or 120 Months

Auxiliary Drive Belt, Inner – Renew

Every 180000 km or 120 Months

Auxiliary Drive Belt Outer – Renew

Every 90000 km or 120 Months


Timing Belt Replacement

Renew timing belt, timing belt tensioner and timing belt idler pulley every 180000 km or 120 months


  • 2009 – 2016 Holden Cruze 1.8L F18D4
  • 2007 – 2010 Holden Astra AH 1.8L Z18XER
  • 2001 – 2005 Holden Astra TS 1.8L Z18XER
  • 2013 – 2015 Holden Trax TJ 1.8L F18D4

AHS has had several occurrences where customers have purchased a new cylinder head for a Holden 1.8L Z18XER or F18D4 engines and fitted it themselves. This has resulted in no oil flow to the cylinder head and the sump filling up with coolant.

Like many other engines, this head gasket can be fitted incorrectly, and it is only after startup where the mistake is made evident. The workshop manual makes no notes on what to look for when refitting the gasket to ensure it is in the correct position.  There are no markings to indicate which way is up.  You must have a look and align the holes yourself.

The oil flow to the cylinder head goes from the block into an elongated hole or teardrop area at the centre cylinder to a bolt hole.  The oil then flows up the bolt hole and in through a gallery to lubricate the head.  If the gasket is flipped over and fitted incorrectly, it will block off oil flow to the cylinder head and causes coolant to enter the oil system from the teardrop cut out in the gasket. The head needs to come off again.

The head bolts are torque to yield and must also be replaced if loosen (See Tech Online for tension specifications), and the head gasket must also be replaced if it has been compressed.

This is not the only engine in which it is easy to fit the head gasket incorrectly, so it is up to you to take care and double check that all the holes are aligning correctly before installing the head.  It might be good practice to take note of the old gaskets orientation and use it as a guide for reassembly. A few minutes at this stage will save you hours of rework, wasted parts and money.

1994 – 2018  Mitsubishi Pajero 2.8L / 3.2L

2006 – 2009 Mitsubishi Triton 3.2L

1995 – 2004 Mitsubishi Delica 2.8L


All Head Services has a recurring problem of customers destroying camshafts and either stripping threads or shearing camshaft sprocket bolts on Mitsuibishi 4M40 and 4M41 engines.  This is caused by the fact that these bolts have a left hand thread.


In the July 2018 issue of Tech Talk (page 4536) we discussed the typical applications of left hand threads and how they are marked.  The convention for identifying a nut or bolt with a left hand thread is with grooves cut into the corners of the hexagon.  However, Mitsubishi have gone their own way.


The camshaft bolts on the 4M40 and 4M41 engines have an arrow cast into the head of the bolt to indicate the tightening direction, which in this case is anti-clockwise.


When these black bolts are covered in black and possibly sludgy diesel oil, these arrows cannot be seen and the bolts do not have the grooves cut into the corners of the hexagon to make it evident that they are a left hand thread.  As a result, technicians are applying excessive torque in the wrong direction to try and undo the bolts which is leading to expensive damage.


If you have been using a rattle gun on these bolts, then realise that you are turning them the wrong way, it is recommended that you replace the bolts, as is it is highly likely that you have streteched the bolt beyond its yield point.


When loosening or tightening the camshaft bolts on these engines, you should hold the camshaft with an open-ended spanner on the hexagon part of the camshaft.  Do not use the timing chain to hold the camshaft as you could damage components or skip teeth.  The torque specifications for these camshaft bolts are:

4M40: 90 Nm

4M41: 88 Nm


Using a left hand thread on the camshaft sprocket is rare and using an arrow on the end of the bolt to identify it is unconventional.  This is another trap to remember when working on these engines.

AHS recently had contact from a customer who had purchase a Nissan Patrol TB42 cylinder head, and after fitting had a complaint of oil in the cooling system.  The cylinder head had been on the vehicle for seven months and had only travelled 2000km.  The vehicle was dual fuel with petrol and LPG.  The cylinder head was removed and sent back to AHS, along with the head gasket

Upon inspection, the head was found to be bent .010″ with the obvious cause being severe detonation (which is uncontrolled combustion).  This had melted the cylinder head around the combustion chamber fire ring area, leading to the head gasket failure, which is how the oil got into the coolant.

With some further investigation, it was discovered that the LPG system on the vehicle was in an unserviceable condition and the owner was instructed to only run it on petrol until the LPG system was fixed. This advice was ignored.

LPG provides a hotter environment in the combustion chamber, which in turn increases the temperature of the cylinder head and if you add detonation into the mix, the head can melt.  In this case, the out of tune LPG system was found to be the cause of the detonation issues and the damage to the engine.

It is imperative with any fuel system and critical with LPG that the engine is kept in tune.  Detonation can be cause by many things, but incorrect ignition timing, ignition advance curve and air/fuel ratio are some of the main culprits.  Duel fuel applications add an extra complication due to the different characteristics of petrol and LPG.

At low rpm, the LPG burn rate is slower, so more ignition advance is needed, at high rpm the LPG burn rate is faster, so less advance is required.

Both of these are the opposite of the requirements of petrol, which can then increase the chance of detonation if the advance curve is not recalibrated.  Also if the air/fuel ratio is too lean, this will increase the speed and temperature of combustion, which again rises the change of detonation.

The customer stated that there was no damage to the bottom end of the engine.  This is lucky, as detonation can easily damage pistons, rings and bearing if it is left unchecked.  AHS were able to repair the cylinder head and returned it to the customer.





AHS has seen first-hand the vast amounts of carbon build up in the intake manifold and ports when rebuilding diesel engines with EGR Systems on them.

The build-up of carbon in crankcase oil has been a problem for some time, but with common rail engines, usually turbocharged and fitted with EGR valves, carbon is building up in the inlet tract at an alarming rate in some engines.

The carbon build up is caused when “Blow-By” gasses with suspended oil particles from the PVC (Positive Crankcase Ventilation) Valve and exhaust gases from the Exhaust Gas Recirculation (EGR) valve full of soot meet in the intake system. They then combine into a wet sticky mess which slowly builds up on the surfaces of the intake manifolds, intake ports and valves.  Short trips around town and low-temperature operation seem to make the build-up worse, high temperature and highway operations seem not to have this problem as much.

Over time this build up can turn hard and brittle which can break off and pass into the combustion chamber and become wedged in the piston ring lands or get lodged between the piston crown and valves or cylinder head.

This carbon build up must be removed completely from the intake system when either rebuilding the engine or replacing the cylinder head. Failure to do so could lead to engine damage or at least reduced performance.

There are not many shortcuts to carbon removal. Use a hot wash only on metal manifolds without plastic brushes for variable intake valves. A hot wash can damage plastic manifolds and internal parts.

Subaru SA459 Upper Cylinder Engine Cleaner seems to be the best product to loosen the carbon deposits.  Then use a bottle brush to get into the tight places.  See the March 2017 issue of Tech Talk and article on cleaning intake manifolds.

To avoid engine damage ensure that the manifolds and ports are meticulously cleaned prior to the engines assembly.

All Head Services recently had a VW Tiguan 1.4L TSI “Twincharger’ CAVD engine sent in for a rebuild due to low compression on number two cylinder.  The engine was dismantled for inspection, and number two cylinder’s piston rings had worn through the ring land of the piston, and the other three pistons had cracks in the ring lands.

These 1.4L TSI Twincharger engines are based on the EA111 engine family. They were designed on the idea of ‘downsizing’ in which a powerful and very efficient smaller capacity engine can do the same jobs as a larger less efficient engine while consuming less fuel.  In this case with a combination of supercharging, turbocharging and direct fuel injection.  These engines have won the award for best engine in the 1.0L to 1.4L class from 2006 to 2014 and was awarded the best overall International Engine of the year for 2009.  (See Tech Talk July 2007 page 2597 for system overview).

They are used in Volkswagen, Golf, Jetta, Scirocco, Tiguan, EOS, Polo and Passat.  Also the Audi A3, Seat Leon and the Skoda Octavia from 2005 to 2013. They have engine I.D. codes starting with CAV or CTH. However, trouble was coming.

The piston issue surfaced early, and Volkswagen started a service campaign (24S4) in 2010 to reduce its occurrence.  It involved reprograming the ECU with recalibrated settings for the knock sensor.  This may have been helpful; however, there was another problem that Volkswagen could not control.

These engines are designed to run on 95 RON unleaded petrol RON stands for Research Octane Number and the higher octane fuel allows the engine to compress the air/fuel mix to a higher compression ratio before detonation occurs.  This makes the engine more efficient.  However, as you have noticed at the service station, the higher the octane rating, the more expensive the fuel gets.

If the owners of the vehicles run the engine on 91 RON fuel because it is cheaper at the pump, it will cause preignition, detonation or pinging, which are all different names for uncontrolled combustion in the combustion chamber. This is combustion which occurs too early which then tries to force the piston back down the cylinder while it is still on the way up on the compression stroke.

Uncontrolled combustion can occur without any audible noise or knocking from the engine. If it occurs for a prolonged period, it will cause the ring lands to crack, the rings will break, which then start to wear their way through the ring lands (as shown in the pictures).  The first signs of this problem will be some rough running, then misfire related codes, but by this time, the damage has been done. A compression test should be conducted to confirm the issue.

These small, high output engines have been designed to perform very well when all of their requirements are met. You should have a chat with your customers with these engines and encourage them to use 95 RON fuel, as recommended in their owner’s handbook.  Otherwise, the money they think they have saved by buying cheaper fuel, probably will not cover the cost of a rebuilt engine.